iOS播放音乐、后台播放、控制台控制相关的一些TIPS，基于St

首先给大家放一个StreamingKit的链接

简单的播放使用例子，可以看开源作者的演示demo。

由于整个播放器涉及到UI啊数据啊比较多，所以就不全抠下来当demo了，就在这里列一点TIPS，希望能帮助到大家。

歌曲播放形式我是这么写的：

.h里：

/**
 歌曲播放形式
 */
typedef enum : NSUInteger {
    MBAudioPlayTypeCircle,  //循环播放
    MBAudioPlayTypeRandom,  //随机播放
    MBAudioPlayTypeOneMusic,//单曲循环
    MBAudioPlayTypeNoNext,  //播完就不播了
} MBAudioPlayType;

.m里：

/**
 *  下一首
 */
- (void)playNextMusic
{
 switch (self.playType) {
        case MBAudioPlayTypeCircle:
        {
            //循环播放
            _nowMusicLocal++;
            if (_nowMusicLocal >= [self allLocal]) {
                _nowMusicLocal = 0;
            }
            [self playMusic];
            
        }
            break;
        case MBAudioPlayTypeRandom:
        {
            //随机播放
            [self randomWithTimes:5];
            
            if (_nowMusicLocal >= [self allLocal]) {
                _nowMusicLocal = 0;
            }
            [self playMusic];
            
        }
            break;
        case MBAudioPlayTypeOneMusic:
        {
            //单曲循环
            [self playMusicWithInfo];
        }
            break;
        case MBAudioPlayTypeNoNext:
        {
            //播完就不播了
            
        }
            break;
        default:
            break;
    }

}

#pragma mark - 随机播放随机数
/**
 *  随机递归
 *
 *  @param num 递归次数
 */
-(void)randomWithTimes:(NSInteger)num
{
    NSInteger randomMusic = arc4random() % [self allLocal];
    
    DLog(@"随机值为：%ld",(long)randomMusic);
    
    if (_nowMusicLocal == randomMusic && [self allLocal] != 1) {
        //防止递归死循环
        if (num != 0) {
            num--;
            [self randomWithTimes:num];
            return;
        }else
        {
            randomMusic++;
            //递归多次还一样，就强行设一个了（低概率事件）
            _nowMusicLocal = randomMusic;
        }
    }
    else
    {
        //正常情况
        _nowMusicLocal = randomMusic;
    }
}

这个随机算法写的其实挺搓的，不过勉强能用吧。。。

获取后台播放权限

在target-capabilities-background modes 开启 audio and airplay

在AppDelegate中

#import <AVFoundation/AVFoundation.h>
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    xxxxx;

NSError* error;
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback error:&error];
}

漏掉最重要的了，在程序挂起的时候，要手动加权限的，

- (void)applicationWillResignActive:(UIApplication *)application
{
    
    DLog(@"\n\n倔强的打出一行字告诉你我要挂起了。。\n\n");
    
//MBAudioPlayer是我为播放器写的单例，这段就是当音乐还在播放状态的时候，给后台权限，不在播放状态的时候，收回后台权限
    if ([MBAudioPlayer shareInstance].audioPlayer.state == STKAudioPlayerStatePlaying||[MBAudioPlayer shareInstance].audioPlayer.state == STKAudioPlayerStateBuffering||[MBAudioPlayer shareInstance].audioPlayer.state == STKAudioPlayerStatePaused ||[MBAudioPlayer shareInstance].audioPlayer.state == STKAudioPlayerStateStopped) {
        //有音乐播放时，才给后台权限，不做流氓应用。
        [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
        [self becomeFirstResponder];
        //开启定时器
        [[MBAudioPlayer shareInstance] decideTimerWithType:MBAudioTimerStartBackground andBeginState:YES];
        [[MBAudioPlayer shareInstance] configNowPlayingInfoCenter];
    }
    else
    {
        [[UIApplication sharedApplication] endReceivingRemoteControlEvents];
        [self resignFirstResponder];
        //检测是都关闭定时器
        [[MBAudioPlayer shareInstance] decideTimerWithType:MBAudioTimerStartBackground andBeginState:NO];
    }
}

锁屏时，更新控制台、锁屏信息（定时器调用）

#pragma mark - 锁屏控制

/**
 *  设置锁屏信息
 */
-(void)configNowPlayingInfoCenter
{
    
    if (self.nowPlayingMusicInfo == nil) {
        return;
    }
    
    
    @autoreleasepool {
        
        NSDictionary *info = self.nowPlayingMusicInfo;
        
        
        NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
        
        //歌曲名称
        [dict setObject:[info ObjectNullForKey:@"title"] forKey:MPMediaItemPropertyTitle];
        
        //演唱者
        [dict setObject:[info ObjectNullForKey:@"author"] forKey:MPMediaItemPropertyArtist];
        
        //专辑名
        //[dict setObject:[info ObjectNullForKey:@"album"] forKey:MPMediaItemPropertyAlbumTitle];
        
        //专辑缩略图
        NSString *imagePath = [info ObjectNullForKey:@"thumb"];
        imagePath = [NSString stringWithFormat:@"EGOImageLoader-%lu", (unsigned long)[[imagePath description] hash]];
        NSString *imageLocalPath = [NSString stringWithFormat:@"%@/%@", EGOCacheDirectory(),imagePath];
        
        NSData * thumbData = [NSData dataWithContentsOfFile:imageLocalPath];
        
        if (thumbData != nil) {
            UIImage *image = [UIImage imageWithData:thumbData];
            MPMediaItemArtwork *artwork = [[MPMediaItemArtwork alloc] initWithImage:image];
            [dict setObject:artwork forKey:MPMediaItemPropertyArtwork];
        }else
        {
            // FIXME: 无图的时候，读取图
            
        }
        //音乐剩余时长
        [dict setObject:[NSNumber numberWithDouble:self.audioPlayer.duration] forKey:MPMediaItemPropertyPlaybackDuration];
        
        //音乐当前播放时间 在计时器中修改
        [dict setObject:[NSNumber numberWithDouble:self.audioPlayer.progress] forKey:MPNowPlayingInfoPropertyElapsedPlaybackTime];
        
        //设置锁屏状态下屏幕显示播放音乐信息
        //DLog(@"显示播放音乐信息：%@\n%@",dict,[info ObjectNullForKey:@"title"]);
        
        [[MPNowPlayingInfoCenter defaultCenter] setNowPlayingInfo:dict];

    }
    
}


/**
 *  响应远程音乐播放控制消息
 *
 *  @param receivedEvent
 */
- (void)remoteControlReceivedWithEvent:(UIEvent *)receivedEvent {
    
    if (receivedEvent.type == UIEventTypeRemoteControl) {
        
        switch (receivedEvent.subtype) {
                
            case UIEventSubtypeRemoteControlPause:
                //点击了暂停
                [self pauseStreamer];
                break;
            case UIEventSubtypeRemoteControlNextTrack:
                //点击了下一首
                [self playNextMusic];
                break;
            case UIEventSubtypeRemoteControlPreviousTrack:
                //点击了上一首
                [self playPreMusic];
                //此时需要更改歌曲信息
                break;
            case UIEventSubtypeRemoteControlPlay:
                //点击了播放
                [self pauseStreamer];
                break;
            default:
                break;
        }
    }
}

最后，那些在锁屏中带歌词的产品么，据说是不停的的把歌词和专辑图片结合在一起，然后根据歌词时间刷新图片。。。如果有这个产品需求，可以按这个思路来做。。

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